Effects of strain and surfaces on the antiferromagnetic and ferromagnetic phases of thin film FeRh

FeRh undergoes an unusual antiferromagnetic (AFM) to ferromagnetic (FM) first order transition just above room temperature. This transition can be tuned by pressure, magnetic field, composition, and strain. The underlying source of the transition is still under much discussion, but it is clear from a variety of measurements that electronic structure, lattice, and magnetic excitations all play roles in contributing the underlying entropy difference and hence the competition between AFM and FM states. The surface and bottom interface of thin films are often found to be FM even while the bulk of the film is AFM. The source of this effect, along with the dependence of strain on both anisotropy and transition temperature will be presented and discussed.